Relay cells of the lateral geniculate nucleus of the cat receive inhibitory retinal ganglion cell input via geniculate interneurons. The nature of this inhibition is to be studied. The type and degree of convergence of ON- and OFF-type and X- and Y-type ganglion cells as inhibitory influences onto the various relay cell types will be studied. Recently discovered simultaneous firing of adjacent ganglion cells will be considered in this analysis. Quantitative cross-correlation techniques are to be used. Spatial white noise analysis will be used to estimate receptive field size of retinal ganglion cells in the cat and the results will be compared, on the same cell, with more conventional area-threshold measurements. Also, second order Weiner kernel analysis will be used to study response non-linearity. Attention will be paid to W, X and Y-type cell classification.